On New Year's Eve, Michael Dasrath was settling into his first-class seat on a Continental Airlines flight from Newark, N.J., to Tampa, Fla.

A consultant for JP Morgan who was originally from Guyana, he was going to visit his family for the holiday. Two other dark-skinned men were sitting in front of him, chatting.

A woman nearby watched them nervously. She got the captain's attention and told him, "those three brown men" are acting suspiciously, according to Mr. Dasrath's account. The captain then asked them to get off the plane.

"I was working downtown on Wall Street on September 11, and I will never forget the horror of that day," says Dasrath. "But ejecting me from a flight to make a passenger feel better isn't going to make anyone safer."

In this post-9/11 world, it's one of a pilot's toughest calls: What to do when there's a complaint about passengers who appear to be of Arab or Middle Eastern dissent. But too often, according to the activists, they're making the wrong call.

Yesterday, Mr. Dasrath became a plaintiff in one of five major discrimination lawsuits filed by the American Civil Liberties Union (ACLU), on behalf of five men and the Arab American Anti-Discrimination Committee (ADC), against United, American, Continental, and Northwest airlines. The men contend they were ejected from flights based not on security concerns, but purely on the prejudice of airline employees and other passengers.

"This denial of service is a new and disturbing form of discrimination that's emerged in this country since 9/11," says Ibish Hussein, of the ADC in Washington. "It's understandable, but it's not acceptable."

Mr. Hussein says the suits have three goals: to get a court order preventing airlines from ejecting passengers without clear cause, to push the Department of Transportation to develop a clear policy to guide airline personnel, and to win damages for the plaintiffs.